Electric Double Layer Capacitors (EDLC), also known as supercapacitors or ultracapacitors, have received much attention recently because of their power delivery performance that perfectly fills the gap between dielectric capacitors and traditional batteries. With the growing development of renewable energy sources as well as Hybrid Electric Vehicles (HEV), where peak power will be needed, these systems may play an important role in complementing or replacing batteries in the energy storage field.
The most advanced devices, e.g. carbon-based supercapacitors, store the energy through reversible ion adsorption on high specific surface area (SSA) carbons at the carbon/electrolyte interface. This surface storage explains the high power capability of these systems. Moreover, because it is believed that there are no Faradic reactions involved in the charge storage mechanism, EDLCs can sustain hundreds of thousands cycles without any noticeable performance change. However, as a consequence of the reversible electrostatic surface charging, these systems suffer from limited energy density. Ongoing EDLC research is largely focused on increasing their energy performance and temperature limit. For example, Carbide-Derived Carbon (CDC) materials seem to defy conventional wisdom about inaccessibility of small pores to solvated ions, tailored sub-nanoporous materials exhibit very high capacitance in an acetonitrile-based organic electrolyte, with a volumetric energy about twice as high as standard, commercial activated carbons. An Ionic Liquid (IL) electrolyte was used to study the capacitive behavior of CDCs with controlled and tunable pore size just below and above the ion size. And TiC-CDCs have recently demonstrated great potential for controlling pore size in supercapacitor materials.
Despite the advances in supercapacitor materials, there is nevertheless a need for a material of controllable porosity capable of equaling or surpassing the energy storage potential of existing supercapacitors. There is also an attendant need for methods for fabricating such supercapacitor materials.